🌈 SketchWave Rainbow Demo

SWRainbow is a SketchWaveJS shape that renders a set of concentric colored arcs — a rainbow! — centered on a single point. Each arc has its own independent color (ROYGBIV by default), so the shape is visually quite different from its geometric sibling, SWWifi.

Shape Parameters

• Number of Arcs — how many concentric arcs to draw (1–10). Default 7 = full ROYGBIV.
• Inner Radius / Arc Spacing — the radius of the innermost arc and the radial gap between arcs (in user/grid units).
• Dot Radius — radius of the filled center dot (same color as innermost arc). Set to 0 for no dot.
• Arc Span (theta) — angular width of all arcs in degrees. 180° = half-circle rainbow; 360° = full rings.
• Direction — which way the arcs open (CCW from +x; default 90° = pointing up).
• Static Rotation — tilts the whole shape before animation.
• Arc Thickness — stroke weight of all arcs in pixels.
• Opacity — alpha for all arcs and the center dot.

Recoloring Arcs

• Click any arc on the canvas to select it (a subtle glow appears on the selected arc). The Arc Colors panel opens automatically.
• Use the color picker to change that arc's color to anything you like.
• Each arc remembers its color independently.
• Click Reset All Colors to ROYGBIV to return to the defaults.

Animations

• Breathing — oscillates the arc stroke weight between Min and Max thickness using a sinusoidal curve. The period controls how slowly it breathes.
• Spinning — rotates the whole rainbow group around its center at a constant speed in degrees/second. Negative rates spin counter-clockwise.

Keyboard Shortcuts

• b — toggle breathing
• s — toggle spinning
• r — factory reset
• q — stop all animations

Compare with SWWifi

SWRainbow and SWWifi share the same geometry (concentric arcs + center dot, same radius formula, same angle math) but are independent classes — not parent/child. SWWifi uses a single arc color + signal-strength dimming logic; SWRainbow gives every arc its own color with no signal metaphor. Forcing a parent/child relationship would create an OOP anti-pattern called "refused bequest" — inheriting a large family of methods you don't want. See the SWRainbow Reference for a detailed discussion.